JPL: Observatories Team Up to Reveal Rare Double Asteroid

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JPL: Observatories Team Up to Reveal Rare Double Asteroid

Post by bystander » Thu Jul 12, 2018 8:38 pm

Observatories Team Up to Reveal Rare Double Asteroid
NASA | JPL-Caltech | 2018 Jul 12
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New observations by three of the world's largest radio telescopes have revealed that an asteroid discovered last year is actually two objects, each about 3,000 feet (900 meters) in size, orbiting each other.

Near-Earth asteroid 2017 YE5 was discovered with observations provided by the Morocco Oukaimeden Sky Survey on Dec. 21, 2017, but no details about the asteroid's physical properties were known until the end of June. This is only the fourth "equal mass" binary near-Earth asteroid ever detected, consisting of two objects nearly identical in size, orbiting each other. The new observations provide the most detailed images ever obtained of this type of binary asteroid.

On June 21, the asteroid 2017 YE5 made its closest approach to Earth for at least the next 170 years, coming to within 3.7 million miles (6 million kilometers) of Earth, or about 16 times the distance between Earth and the Moon. On June 21 and 22, observations by NASA's Goldstone Solar System Radar (GSSR) in California showed the first signs that 2017 YE5 could be a binary system. The observations revealed two distinct lobes, but the asteroid's orientation was such that scientists could not see if the two bodies were separate or joined. Eventually, the two objects rotated to expose a distinct gap between them. ...
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Re: JPL: Observatories Team Up to Reveal Rare Double Asteroid

Post by neufer » Fri Jul 13, 2018 12:22 pm wrote: <<Sabine is a lunar impact crater that forms a nearly matching pair with Ritter to the northwest. The two rims are separated by a distance of only a couple of kilometers. About 85 km to the east-southeast is 'Statio Tranquillitatis' (Tranquility Base), the landing site of the Apollo 11 mission and the first human beings to step on the Moon.

Both Sabine and Ritter were originally believed to be calderas rather than impact craters. In To A Rocky Moon, lunar geologist Don E. Wilhelms summarized: "They are identical twins in morphology and size (29-30 km). They lack radial rim ejecta and secondary craters despite their apparent youth. They are positioned at the presumably active edge of a mare. They are even aligned along graben, the Hypatia rilles. Most significant, they lack deep floors recognized since the days of Gilbert as diagnostic of impacts." However, after the Apollo landings were complete, it was realized that "all craters inside basins suffer enhanced isostatic uplift," because "the thin crust and greater heat inside basins lower the viscosity of the craters' substrate, allowing it to reach isostasy with its surroundings more quickly than can other craters.">>
Art Neuendorffer